ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

previous: Charlie Circuit problem... -- 5/10/2000 12:17 AM

Re: Circuit problem...revised...

5/11/2000 1:10 AM
Charlie	Re: Circuit problem...revised... Thanx for all the input Ok.. I found what was causing the whine from the circuit. I had placed a .01uF mylar cap where a .1uF cap should go, replaced it and whine is gone. Got to get my eyes checked for sure Now when circuit is connected and switch thrown, no sound. Tested out all the connections with the multi-meter for continuity and checks out where it supposed to be. Taking RG's advice I've taken voltage readings with circuit under load for the TL072 IC: Pin 1 = 7.11v Pin 2 = .6v Pin 3 = .59v Pin 4 = 1.15v Pin 5 = 1.2mv Pin 6 = 284.9mv Pin 7 = 1.258v Pin 8 = 6v Diodes used are 1N4148 and voltage readings for the lower four on the left of the layout going left to right measured fron the non cathode end: .46v .58v .60v .96mv Diode in upper middle postion read: 8.02v Caps used are all mylar except: 47pF = ceramic .1uF = metalized film 100uF = electrolytic I know I've bungled this up somehow but not sure where. All the advice is very much appriciated. If all else fails I will start over from scratch but I would really like to debug this one. Thanks again all... Charlie

5/11/2000 1:10 AM

Charlie

Re: Circuit problem...revised...

Thanx for all the input ;-)

Ok.. I found what was causing the whine from the circuit. I had placed a .01uF mylar cap where a .1uF cap should go, replaced it and whine is gone. Got to get my eyes checked for sure ;-)

Now when circuit is connected and switch thrown, no sound. Tested out all the connections with the multi-meter for continuity and checks out where it supposed to be. Taking RG's advice I've taken voltage readings with circuit under load for the TL072 IC:

Pin 1 = 7.11v
Pin 2 = .6v
Pin 3 = .59v
Pin 4 = 1.15v
Pin 5 = 1.2mv
Pin 6 = 284.9mv
Pin 7 = 1.258v
Pin 8 = 6v

Diodes used are 1N4148 and voltage readings for the lower four on the left of the layout going left to right measured fron the non cathode end:

.46v
.58v
.60v
.96mv

Diode in upper middle postion read:

8.02v

Caps used are all mylar except:

47pF = ceramic
.1uF = metalized film
100uF = electrolytic

I know I've bungled this up somehow but not sure where. All the advice is very much appriciated. If all else fails I will start over from scratch but I would really like to debug this one. Thanks again all...

Charlie

Replies:

R.G. Well, good folks, we got trouble, <... -- 5/11/2000 3:28 AM